High quality digital cameras typically employ multiple image sensors so that a separate image sensor may be used to process data for a red color component, a blue color component and at least one green color component. In such systems, a beamsplitter such as a color separation prism is typically employed to split light received through a lens into the respective red, blue and green color components. Each respective color component is delivered to an image sensor associated with that color component. Accurate positioning of the beamsplitter relative to the individual image sensors is needed to ensure the best picture quality possible. Indeed, accurate positioning of the image sensors relative to the beamsplitter on the sub-micron level is desirable.
Examples of environmental, production and functional factors that may have an impact on the positioning accuracy of an image sensor include temperature, humidity, external forces, internal stress within adhesives, fixation methods or the like. Additional factors that may be relevant when positioning an imager relative to associated optical components include the desire to reduce material costs, the desire to increase the recycle-ability of image sensors, the desirability of good cleaning condition of glass surfaces to increase yield, the displacement of components during fixation or the like.
A known photo-electric conversion device generates electrical signals in response to the light from an optical system including a prism assembly having plural light emitting faces. The prism assembly separates the light from the optical system into plural light components, including plural solid-state sensors adjoining the light emitting faces of the prism assembly. The light emitting faces and image sensors are provided with adhering or metalized areas to fix a first surface of a spacer with glue or solder onto each light emitting face and sensor image. Each spacer has a second metalized surface appropriate for stiffly connecting one solid-state sensor to the prism by soldering or adhering.
U.S. Pat. No. 5,042,913 to Yamamoto discloses an apparatus for firmly mounting solid-state image sensors to an image splitting prism in which a mounting glass block is bonded to an image splitting prism surface or to a glass plate bonded to a prism. A metal film is formed on the glass block, and a preliminary solder layer is formed on the metal film to improve wettability. A gap between the preliminary solder layer and a meltable metal member formed on a caging of a solid-state image sensor is filled with a meltable metal having a predetermined thickness, thus bonding the preliminary solder layer and the meltable metal member. When this construction can be obtained, the total thickness of the metal film can be reduced to 1.mu.m or less.
U.S. Pat. No. 5,340,420 to Ozimek, et al. discloses a method for bonding a color separation filter to an image sensor. The method comprises the steps of dispensing an optical coupling composition on a preselected surface of at least one of the filter and sensor, bonding the filter to the sensor for creating a filter-sensor assembly, by using a predetermined amount of ultraviolet (UV) curable adhesive at an interface of the filter-sensor assembly, and dispensing an epoxy along a periphery of the filter-sensor assembly, thereby encapsulating the optical coupling composition at the interface of the filter-sensor assembly.
U.S. Pat. No. 6,256,118 to Moriarty, et al. discloses a film scanner in which a CCD image sensor is aligned to a film plane scanning aperture and is mounted to the an intervening imaging housing assembly by means of a radiation (UV) curable adhesive of appropriate viscosity. With the sensor positioned within but in spaced apart relationship to a sensor housing segment of the housing assembly, the adhesive is injected through a mounting hole in a wall of the housing segment to adhere to the image sensor. An excess amount of the injected adhesive forms a cap over the mounting hole. The viscosity of the adhesive is selected such as to allow the adhesive to generally maintain its shape in the space between the sensor and the wall of the sensor housing segment. The spacing of the sensor from the sensor housing segment allows six degrees of freedom of movement of the sensor during the alignment operation after which the injected adhesive is curing in situ to form a sensor mount fastener with the sensor is precise alignment with the film plane aperture. The hardened cap over the mounting hole provides a solid mechanical bond of the fastener to the housing segment.
U.S. Patent Publication No. 20050195503 to Chen discloses a digital camera module for a portable electronic device. The digital camera module includes a barrel containing a first lens and a second lens, a holder containing part of the barrel, and an image sensor below the first and second lenses. The first and second lenses are adhered in the barrel by an ultraviolet (UV) adhesive. The UV adhesive is cured between 75.degrees Celsius and 100.degrees Celsius for 20 to 30 minutes, and is volatilized little. The image sensor is packaged with a Ceramic Leaded Chip Carrier. The structure of the digital camera module is intended to effectively protect the first and second lenses thereof from moisture, dampness, and oxidation.
U.S. Patent Publication No. 20020006687 to Lam discloses an IC chip package for an image sensitive, integrated circuit semiconductor die that incorporates all the components typically found in an imaging module of an electronic camera. The IC chip package consists of a plastic substrate base for holding an image sensor die and a separate, plastic upper cover for encapsulating the image sensor die and holding a filter glass, an optical lens, and providing an aperture for the optical lens. The upper cover has a lower shelf for holding the optical lens in alignment with the aperture opening over the image sensor die, and has an upper shelf for holding the filter glass over the optical lens. The lens is attached to the lower shelf using UV cure adhesive, and its focal distance to the image sensor die is determined by first electrically activating the image sensor die, adjusting the lens position to identify the optimal focus sharpness, and then applying UV light to activate the UV cure adhesive and hold the lens in focus.